Process of regenerating oil used for electrical purposes.



,umrnn ,STATES PATENT OFFICE.

ROBERT muEsE; or cnennorrnnnune, GERMANY, ASSIGNOR r0 SIEMENS,-

scnucxnnrwnnxn, e. M. B. H., or BERLIN, GERMANY, A CORPORATION OFGERMANY.

PROCESS OF REGENERATING OIL, USED FOR ELECTRICAL PURPOSES,

Ho Drawing.

pecification f Le ters Patent. Patented July 14, 1914. Application filedApril 1, 1913. Serial No. 758,246.

I To all whom it may concern:

Be it known that I, ROBERT Fnmsn, a citizen of the German Empire, andresidlng at Gharlot-tenburg, near Berlin, Germany, have invented acertain new and useful Improved Process of Regenerating Oil Used forElectrical Purposes, of which the following is a specification.

The subject-matter of my invention is a process of rendering oil used astransformer oil or the like usable again for electrical purposes.

Electrical apparatus, such as transformers, resistances, switches andthe like, subjected to high tensions are frequently placed in anoil-bath for the purpose of insulating and cooling them better thanwould otherwise be the case. Bot-h these ends can be attained only whena sufficiently large quantity of oil is employed, so that the oilfrequently represents a not inconsiderable part of the entire value ofthe apparatus. In economical respects it is therefore veryunsatisfactory that the oil-filling loses its good properties more andmore in the course of time when the apparatus is in use, and even if theoil becomes entirely unusable possibly only after a long .period, thesubstitution .of the used oil by fresh nevertheless causes anappreciable loss apart from the fact that the reliability of theapparatus is diminished during a long time. cially purified mineral oilfrequently employed for the purposes in question loses its light clearcolor, darkens, becomes more and moreturbid and viscous, and solidconstituents are precipitated and settle as muddy or solid matter,thereby more and'more diminishing and finally negativing the efficacy ofthe oil. The reasons for the change inthe oil in consequence of theelectrical apparatus being used cannot as yet be exactly stated. Thereis, however, great need for a process by means of which the oil can beregenerated, thus giving back to it all those properties which arenecessary for electrical apparatus, it being unimportant whether changesare thereby made in the oil which render it of little value for otherpurposes or not. 4

A primary object of my invention is to provide such a process whichmeets this want. To this end, the pil to be regenerated removed from theelectrical apparatus is The spegravity gradua lly separate, and aftersome time two clearly defined portions of the liquid can be observed;that at the top is the lighter acetone which can be readily poured offand contains in solution those noxious constituents of the oil whosepresence was the reason of the oil being impaired, whereas the lowerlarger portion of the liquid is the regenerated oil containing, it istrue, a considerable percentage of acetone. As this percent-age ofacetone renders the oil readily inflammable it must be removed therefrombefore the oil is again employed in electrical apparatus. It can howeverbe very readily removed from the oil by distillation and 'be recoveredWithout material loss by condensation. In the same manner the acetonecan for the most part be recovered also from the upper portion of theliquid consisting of acetone and the injurious constituents of the oildissolved in it.

The described processis of peculiar economic value because it can bereadily carried into practice, is very efiective and in spite of the notinconsiderable price of acetone, is also very economical on account ofits being possible almost completely to recover the acetone.

The following practical example Will illustrate the carrying out of myinvention:

40 cm of acetone are added to 100 cm of used oil, of which about 20 cm?of the acetone goes into the oil, While the remaining 20 cm of acetone,Which contains the impurities to be removed, separates from theoil-acetone mixture mechanically in a layer and can be removedtherefrom. The ace tone remaining in the oil can be separated andrecovered. by distillation.

Besides acetone, other solvents, e. 9, methyl alcohol, have proved to beeffective 'in a similar manner asacetone. Their action is however somuch weaker than that of acetone that they are not of much importance inpractice.

I claim A process of regenerating oil used as transformer oil or thelike for electrical purposes, oonsisting in mixing the used oil withacetone, in leaving the mixture thereby obt-ained at rest whereupon itsconstituents of In testimony whereof I have signed my different specificgravity separate in two name to this specification in the presence ofsuperposed layers, in removing the upper two Witnesses.

layer containing acetone and noxious oon- ROBERT F RIESE. 5 stituents ofthe used oil, and in distilling WVitnesses:

off from the lower layer the residue of ace- VVOLDEMAR HAUPT,

I tone remaining therein. HENRY HASPER.

